LEDs (light-emitting diode) have lately been used widely as an illuminator, light source for a projector, backlight of liquid crystal television, etc. Since the LED dissipates no excessive heat and has an overwhelmingly long life, it attracts more attention because of its possibility of replacing the fluorescent lamp in future. Among others, the practical application of the blue LED has led to development of LED-based signals, full-color LED display devices, etc. and such LED-based products have rapidly become popular. Along with such prevalence of the LED products, it is more and more demanded to improve the performance of the LED.
There is disclosed in the Japanese Published Unexamined Patent Application No. 2002-80733 (Patent Document 1), for example, an LED encapsulant material made from a composition containing, as critical components, an organic compound made up of an organic skeleton containing at least two carbon-carbon double bonds reactive with SiH group in one molecule, a silicide compound containing at least two SiH groups in one molecule and a hydrosilylated catalyst and which thus has a high heat resistance, low birefringence, small photoelastic coefficient, improved transparency and high toughness.
Also there is disclosed in the Japanese Published Unexamined Patent Application No. 2002-317048 (Patent Document 2), for example, an LED encapsulant material made from an aliphatic organic compound having at least two carbon-carbon double bonds reactive with SiH group and one to six vinyl groups and of which the molecular weight is under 900 and viscosity is under 1000 P (poises), a hardener produced by hydrosilylating a chain and/or cyclic polyorganosiloxane having at least two SiH groups and which thus has at least two SiH groups or an organic compound given by the following formula (1), and a hardenable compound produced by hydrosilylating a cyclic polyorganosiloxane having at least two SiH groups and which thus has at least two SiH groups:
where R1 indicates a univalent organic group whose carbon number is 1 to 50; these R1 may be different from or equal to each other.